A fluid control valve for controlling fluid is heretofore used in for example a cleaning step of a semiconductor manufacturing device. In the cleaning step, when an application agent applied to wafers is to be removed, an amount of a cleaning fluid such as acid to be supplied is controlled by a fluid control valve. This fluid control valve includes a fluid contact surface made of corrosion-resistant material to control even high corrosive fluid.
FIG. 7 is a cross sectional view of a conventional fluid control valve 101. FIG. 8 is a view showing a fixing structure of the fluid control valve 101 shown in FIG. 7. FIG. 9 is a top view of the fluid control valve 101 shown in FIG. 7. The conventional fluid control valve 101 includes a valve section 102 and a drive section 103 and will be attached to any device through a mounting plate 110. The valve section 102 includes a resin valve body 120 having a first port 121 and a second port 122 communicating with each other through a valve chamber 123. This valve chamber 123 is provided with a valve seat face 124 around an opening communicating with the first port 121. A diaphragm 125 molded of resin includes a valve element portion 125a movable into or out of contact with the valve seat face 124, a thin web portion 125b formed to be elastically deformable, and a peripheral portion 125c clamped between the valve section 102 and the drive section 103.
The drive section 103 is formed with a piston chamber 134 between a cylinder 131 and a cover 132. In the piston chamber 134, a piston 135 is housed. This piston 135 is attached with a rubber sealing member 141 placed to slide in contact with an inner wall of the piston chamber 134 and to hermetically divide the piston chamber 134 into a first chamber 134a and a second chamber 134b. A piston rod 136 protrudes from the drive section 103 into the valve section 102 and is connected to the valve element portion 125a of the diaphragm 125. On the outer periphery of the piston rod 136, a rubber sealing member 140 is mounted to slide in contact with the cylinder 131 to prevent cleaning fluid permeated and vaporized through the web portion 125b from leaking from the valve section 102 to the drive section 103. In the first chamber 134a, a spring 139 is placed in a compressed state. The first chamber 134a communicates with an air exhaust port 132a. The second chamber 134b communicates with an operation port 131a through which operation air will be supplied.
The above fluid control valve 101 is configured such that the piston 135 is moved up and down in the figure according to the balance between the elastic force of the spring 139 and the pressure of the operation air supplied to the second chamber 134b, thus moving the diaphragm 125 into or out of contact with the valve seat face 124, thereby controlling a cleaning fluid allowing to flow between the first port 121 and the second port 122.
In the above conventional fluid control valve 101, parts or members excepting the spring 139 and the sealing members 140 and 141 are made of resin in order to ensure corrosion resistance. In the cleaning step, the fluid control valve 101 controls a cleaning fluid of 160° C., for example. As shown in FIG. 8, the valve section 102 and the drive section 103 are fastened to each other by screwing fixing screws 146 and 147 from above and below in nut members 148 formed by insert in the cylinder 131 to prevent loosening of their connection due to creep deformation of the parts or members. As shown in FIGS. 8 and 9, the fixing screws 146 and 147 are covered by resin caps 151 and 152 respectively to avoid exposure to corrosive atmosphere (see for example Patent Documents 1 and 2).